The present invention relates to liquid dispensing, particularly of viscous liquids such as liquid soap.
The conservation and sanitary advantages of automatic flow control in sinks and similar installations are well known, so many public rest-room facilities have provided automatic faucets and flushers. Although there is a similar advantage to making liquid soap dispensing automatic in such installations, the popularity of doing so has not been particularly great so far.
Much of the reason for this slow acceptance is installation difficulty. Installing a liquid-soap dispenser often requires providing extra wiring. One solution to this problem is to employ battery-operated systems. This approach is now popular for retrofitting manual flushers to make them automatic, but the power required to pump liquid soap, which can be fairly viscous, is significant. This tends to make battery life in liquid-soap dispensers too short unless the batteries are unacceptably large.